1. Field of the Invention
The present invention relates to internal combustion engines. More particularly, the present invention relates to a blowby control system and method for an internal combustion engine on a vehicle.
2. Description of the Background Art
Internal combustion engines are used for many applications today, and are particularly useful as vehicular power sources. A number of known systems have been proposed to cope with blowby gases, caused primarily by air bypassing the compression rings. Many vehicles are equipped with positive crankcase ventilation (PCV) systems as standard equipment, to help manage blowby gases.
In an internal combustion engine in which blowby gas from a crankcase is not discharged outside of the engine, but instead, is returned to a combustion chamber from an air-intake channel via a breather channel and is then burned, there is an example of a known approach in which a solenoid valve is interposed in the breather channel. (see, for example, Japanese Published Patent Document JP-A-9-68028).
In the system disclosed in this reference, the breather channel is closed during deceleration when the intake vacuum increases to an abnormally high level, for limiting suction of the blowby gas into the combustion chamber.
Therefore, since the blowby gas is drawn into the combustion chamber by a significant air-intake negative pressure with the throttle valve closed or throttled, when a vehicle starts traveling, the engine speed varies due to the combustion of HC mixed in the blowby gas. In particular, in a vehicle having a drive clutch, variations in the engine speed affect the feeling of engagement of the clutch before the clutch is fully engaged.
Although the known blowby control systems are usable for their intended purposes, a need still exists in the art for an improved blowby control system and method. In particular, there is a need for an improved blowby control system and method which will overcome the difficulties encountered with the known art.